IN operator can be achieved by using 'Contains'
Sample below
List<int> input = new List<int>() { 8, 11, 18, 26, 1, 14, 17, 25, 27, 30, 5, 6, 7, 20, 21, 22, 12, 13, 19, 24 };
List<int> source = new List<int>() { 8, 11, 18, 26, 1, 14, 17, 25, 27, 30, 5, 6, 7, 20, 21, 22, 12, 13, 19, 24 };
var acoTransaction = source.Where(p => input.Contains(p) ).ToList();